USMLE Pediatric Surgery

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Cyclic vomiting syndrome

Diagnostic criteria of

• more than 3 episodes in a 6-month period

• Easily recognizable to family (stereotypical)

• Lasts 1- 10 days

• Vomiting more than 4 times/hr at peak

• No symptoms in between vomiting episodes

• No underlying condition can be identified

There is increased risk if In the context of a family history of migraines

Complications: anemia and dehydration due to recurrent vomiting.

Treatment consists of hydration, antiemetics (eg, ondansetron), and reassurance of the parents.

Children with a family history of migraines are likely to benefit from anti-migraine therapy such as sumatriptan.

Approximately 2/3 children with CVS have gradual resolution of their symptoms in 5-10 years

Cystic fibrosis (CF),

the most common autosomal recessive disorder in those of white ethnicity, is characterized by defective chloride transport resulting in viscous secretions in the lungs, sinuses, and pancreas

Clinical features of cystic fibrosis

Respiratory:

• Obstructive lung disease - bronchiectasis

• Recurrent pneumonia

• Chronic rhinosinusitis

Gastrointestinal:

• Obstruction (10%-20%)

o Meconium ileus

o Distal intestinal obstruction syndrome

• Pancreatic disease

o Exocrine pancreatic insufficiency : MC GI manifestation

o CF-related diabetes (-25%)

• Biliary cirrhosis

Reproductive:

• Infertility (>95% men, -20% women)

Musculoskeletal:

• Osteopenia - fractures

• Kyphoscoliosis

• Digital clubbing

Pancreatic insufficiency is present from birth in most patients with CF and results in inability to absorb fats and fat-soluble vitamins (A, D, E, and K), leading to steatorrhea (greasy, foul-smelling stools), failure to thrive, and vitamin deficiencies.

Meconium ileus is virtually diagnostic for CF. Although only 20% of patients with CF develop meconium ileus, almost all newborns with meconium ileus have CF.

Pathogenesis: A mutation in the CF transmembrane conductance regulator gene results in abnormal chloride and sodium transport and thick. viscous secretions in multiple organs. Thick, inspissated meconium is difficult to propel, resulting in obstruction at the level of the ileum and a narrow, underdeveloped colon (microcolon).

Although contrast enema is typically performed to assess level of bowel obstruction , if perforation occurs , free air can be viaualised on the X-ray.

Administration of hyperosmolar enema (eg, Gastrografin) can potentially break up the inspissated meconium and dissolve the obstruction.

Surgery is required if therapeutic enema is unsuccessful.

Nearly all patients with CF develop sinopulmonary disease. Opacification of all sinuses can be seen as early as age 8 months, and patients often require surgical debridement of their sinuses.

Dehydration in Children

The initial step in managing children with dehydration is to determine its severity.

The ideal method of assessing dehydration is to determine the measured change in weight because 1 kg of acute weight loss equals 1 L of fluid loss.

A child's weight, however. changes constantly, making it difficult to obtain an accurate recent "well" weight. Therefore, the degree of dehydration often has to be determined by the clinical history and physical examination. which can be divided into the following categories:

1. Mild dehydration (3-5% volume loss) presents with a history of decreased Intake or increased fluid loss with minimal or no clinical symptoms.

Management depends on the object's material, location in the gastrointestinal tract, timing of ingestion, and symptoms.

This patient's x-ray reveals a flat, homogenous, radio opaque object, most likely a swallowed coin, in the upper esophagus.

Coins are the most common foreign body ingested by children.

If a coin is visualized in the esophagus and the patient is symptomatic or if the time of ingestion is unknown, the coin should be removed promptly.

Flexible endoscopy is the diagnostic and treatment method of choice because the foreign body can be directly visualized and manipulated, and the surrounding gastrointestinal tract can be examined for complications.

Rigid endoscopy has a higher risk of esophageal abrasion and perforation and is usually reserved for impacted sharp objects in the proximal esophagus.

Differential Diagnosis Of vomiting and regurgitation In Children

Gastroesophageal reflux in infant

Is extremely common and affects more than 50% of infants. Normally, healthy people of all ages have small amounts of gastric contents reflux into the esophagus.

These differences include a shorter esophagus, incomplete closure of the lower esophageal sphincter, and greater time spent in the supine position.

Most infants are otherwise asymptomatic (eg. "happy spitter"), and parents should be reassured if examination, growth, and development are normal.

Diagnosis is based on history and physical examination.

Treatment consists of education and supportive measures. Parents should be advised to give frequent, small-volume feeds; hold the infant upright for 20-30 minutes after feeds; and place the infant prone when awake.

Activities that increase intraabdominal pressure (eg, fastening the diaper too tight, bringing the knees to the stomach) should be avoided.

Regurgitation usually improves around age 6 months (when the infant can sit unsupported) and resolves by age 1 year.

Pediatric abdominal wall defects

Diagnosis Clinical features

Umbilical hernia

• Defect at linea alba covered by skin

• Sometimes contains bowel

• Umbilical cord inserts at apex of defect

Gastroschisis

• Defect to the right of the cord insertion not covered by membrane or skin

Second-trimester sonography is more than 95% sensitive for abdominal wall defects, and maternal serum a-fetoprotein is usually elevated.

Gastroschisis results in the bowel being exposed to amniotic fluid, which causes inflammation and edema of the bowel wall.

This inflammation increases the risk of complications (eg, necrotizing enterocolitis, short bowel syndrome). Dysmotllity (ileus, delayed gastric emptying, intolerance of feeds) occurs in over 50% of cases and may lead to prolonged reliance on total parenteral nutrition.

Gastroschisis is an isolated defect >90% of the time.

After delivery, the exposed bowel should be covered with sterile saline dressings and plastic wrap to minimize insensible heat and fluid losses.

The infant should have a nasogastric tube placed to decompress the bowel and should be started on antibiotic therapy.

Prompt surgical repair is necessary and can usually be accomplished in a single-stage closure.

Hirschsprung disease

is associated with Down syndrome, which in turn is associated with an increased risk of Alzheimer disease and hypothyroidism.

Hirschsprung disease should be suspected In any neonate who has delayed passage of meconium as 99% of full-term infants stool within 48 hours of birth.

It is due to failed development of the enteric nervous system of a variable portion of the distal gut and most commonly involves the rectosigmoid.

Rectal examination: can produce an increased rectal tone with explosive expulsion of gas and stool ("squirt sign") from temporary relief from the obstruction.

If there Is no evidence of perforation (eg, free air under the diaphragm), contrast enema can potentially delineate the level of obstruction.

A transition zone: may be seen between the narrowed aganglionic segment and the normally innervated, dilated colon (megacolon).

The gold standard for diagnosis: is rectal suction biopsy, which demonstrates the absence of ganglion cells.

The treatment of choice: is surgical resection of the aganglionic segment followed by anastomosis of the normal bowel to the anus.

Infantile hypertrophic pyloric stenosis

Risk factors:

• First-born boy

• Erythromycin

• Formula feeding (is also thought to cause gradual hypertrophy of the pylorus until symptom onset at age 3-5 weeks. Compared to breastfed infants, formula-fed infants have slower gastric emptying and consume more volume in less time. The increased gastric burden may stimulate growth of the pylorus muscle)

Clinical presentation:

• Projectile nonbilious emesis followed by hunger (eg,

"hungry vomiter")

• Poor weight gain

• Dehydration

A peristaltic wave moving from left to right across the upper abdomen may also be seen immediately prior to emesis.

• " Olive-shaped" abdominal mass palpable in less than 50% of cases. It is best felt when the patient is calm after emesis as the distended stomach can obscure the mass. However, the abdomen is soft and nondistended because minimal air can pass the gastric outlet.

Laboratory findings:

•hypochloremic, hypokalemic metabolic alkalosis

Diagnostic studies:

• Abdominal ultrasound which demonstrates a thick and elongated pylorus.

Treatment:

• Infants with signs of dehydration or laboratory abnormalities should be admitted for intravenous rehydration and normalization of electrolytes prior to definitive surgical treatment. Normalization of electrolytes and correction of alkalosis prior to surgery have been shown to decrease the risk of postoperative apnea and improve overall outcomes.

• Pyloromyotomy

Laboratory Dearrangements In Pyloric Stenosis

Duodenal atresia

Associated with Down Syndrome

Classically presents with bilious vomiting within the first 2 days of life.

The abdomen is not distended due to inability for gas to pass the duodenum.

Prenatal ultrasound: shows polyhydramnios due to inability to swallow and remove amniotic fluid.

X-ray: shows air trapped in the stomach and the first portion of the duodenum ("double bubble sign") and no distal intestinal gas.

Management: includes holding enteral feeds, decompression with a nasogastric or orogastric tube placed to suction, and surgical repair.

Jejunal Atresia

Bilious emesis, abdominal distension and x-ray findings in this neonate are consistent with jejunal atresia.

Intestinal atresia can occur anywhere along the gastrointestinal tract. Atresia of the jejunum or ileum is thought to occur due to a vascular accident in utero that causes necrosis and resorption of the fetal intestine, sealing off and leaving behind blind proximal and distal ends of intestine.

Risk factors: include poor fetal gut perfusion from maternal use of vasoconstrictive medications or drugs such as cocaine and tobacco.

Some cases have been associated with meconium ileus/cystic fibrosis during which inspissated meconium causes a localized volvulus that results in ischemic necrosis.

In contrast to duodenal atresia, jejunal and ileal atresia are not associated with chromosomal abnormalities.

The presence of the "triple bubble" sign and gas less colon on abdominal x-ray reflects gas trapping in the stomach, duodenum, and jejunum.

Treatment should be focused initially on resuscitation and stabilization of the patient, followed by surgical correction.

The prognosis depends on the length of affected bowel as well as the patient's gestational age and birth weight.

Intussusception.

Telescoping of one bowel segment into another.

Intussusception is the most common cause of intestinal obstruction in children age 6-36 months.

Ileocolic junction is most frequently involved, with invagination of the ileum into the colon.

Most children (-75%) have no identifiable lead point. Preceding viral infections (eg, gastroenteritis) are thought to play a role in inflaming intestinal lymphatic tissue (eg. Peyer patches) which can subsequently serve as a lead point for intussusception.

Meckel's diverticulum, followed by polyps and hematomas (Henoch-Scholein purpura), are the most commonly identified triggers in the remaining 25%. Classically, the telescoping is intermittent, resulting in periodic pain associated with drawing the legs up toward the abdomen.

Emesis may follow episodes of abdominal pain. It is initially nonbilious but becomes bilious as the obstruction persists.

Occasionally, the intussusception is palpable as a tubular "sausage-shaped" mass in the right upper quadrant.

Although the ileocecal junction is normally located in the right lower quadrant, the invagination of the ileum into the colon causes the obstructive mass to be found in the right upper quadrant.

Ultrasound is the method of choice in detecting intussusception and has a sensitivity and specificity of 100% if performed by an experienced sonographer during the period of pain.

The positive finding of the "target sign" should prompt immediate enema reduction.

Air or water-soluble contrast is instilled through the rectum and the pressure from these mediums successfully reduces most obstructions.

Air enemas are preferred because they are typically faster, cleaner, and safer than contrast.

Pruritic urticarial papules and plaques of pregnancy (PUPPP)

Is a skin condition that develops in the third trimester. The classic finding on abdominal examination is red papules within striae with sparing around the umbilicus, sometimes extending to the extremities.

The palms, soles, and face are rarely involved, helping to distinguish it from ICP.

There are no laboratory or liver abnormalities associated with PUPPP.

Biliary atresia

caused by progressive obliteration of the extrahepatic biliary ducts connecting the liver to the small bowel

Clinical features:

lnitially well-appearing, followed by development of the following over 1-8 weeks:

Virtually all patients will require liver transplantation, but the Kasal procedure allows time for growth and reduces the morbidity and mortality of hepatic transplant.

Without treatment, the liver will become Inflamed (eg, hepatomegaly, hepatitis) and eventually fibrose.

Jaundice in Neonate

Breast milk jaundice: generally appears in the second week of life. However, the hyperbilirubinemia that occurs is indirect (unconjugated) and may rise as high as 10-30 mg/dl. It Is generally a benign condition, but in rare cases phototherapy may be indicated.

Physiologic jaundice: is unconjugated hyperbilirubinemia that appears after the first 24 hours of life and resolves within the first week. Conjugated hyperbilirubinemia is always pathologic.

Allolmmune hemolytic disease (erythroblastosis fetalis): is characterized by unconjugated hyperbilirubinemia and Coombs-positive hemolytic anemia. It Is caused by a mismatch between Infant and maternal blood types (eg, Rh disease, ABO incompatibility, or minor blood group antigens

Biliary cysts (or choledochal cyst)

Is a congenital dilatation of the biliary tree. These dilatations may be single or multiple and can be intra- or extrahepatic. It can be congenital or acquired.

Should be suspected in a newborn with cyanosis that is aggravated by feeding and relieved by crying.

The congenital nasal malformation is caused by failure of the posterior nasal passage to canalize completely, leaving either a bony (90%) or membranous (10%) obstruction.

The condition may be isolated or part of a syndrome (ie, CHARGE syndrome: Coloboma, Heart Defects, Atresia choanae, Retardation of growth/development, Genito-urinary anomalies, and Ear abnormalities/deafness).

The clinical severity depends on the lnfants ability to breathe through the mouth and whether one or both choanae Is/are obstructed.

Bilateral obstruction classically presents with cyclic cyanosis that worsens when infants cannot breathe through the mouth (eg, during feeding) and recovers when they do (eg, while crying).

Unilateral choanal atresia may remain undiagnosed until the development of a first upper respiratory Infection.

Failure to pass a catheter through the nares into the oropharynx is suggestive of choanal atresia.

The diagnosis is confirmed by CT scan. In contrast to infants with patent choanae, Infants with choanal atresia have narrowing at the level of the pterygoid plate in the posterior nasal cavity.

In severe cases, air fluid levels may develop at the obstruction site.

The first step in management: consists of placing an oropharyngeal airway and orogastric tube feeding. Definitive treatment: involves repairing the obstruction with surgery or endoscopy.

Differential Diagnosis of Crying Infant

Infantile colic

is defined as excessive crying for ~3 hours a day, ~3 days a week, over a period of ~3 weeks in an otherwise healthy infant.

Colic usually presents in the first few weeks of life and resolves spontaneously by age 4 months.

The crying generally occurs at the same time of the day, typically early in the evening.

The cause of colic is unknown but may be due to overstimulation of the Infant and parental unfamiliarity with alternate soothing methods.

Parents often report difficulty and frustration with consoling the infant.

3. Enterohepatlc recycling: is increased as the sterile newborn gut cannot break down bilirubin to urobilinogen for fecal excretion. More bilirubin is resorbed in the gut and recycled in the enterohepatic circulation until the gut is colonized and produces bacterial enzymes for reduction to urobilinogen.

Physiologic jaundice of the newborn

is usually benign and resolves on its own by age 1-2 weeks.

Newborns should be monitored for persistent or worsening jaundice as high levels can cause brain damage.

Frequent feeding should be encouraged to promote gut colonization and fecal excretion.

Natural sunlight can help decrease bilirubin but is not recommended due to risk of sunburn.

In addition to jaundice, infants with breastfeeding failure are often dehydrated.

During the first week of life, the normal number of wet diapers a day should equal the infant's age in days (eg, a 4-day-old infant should have >4 wet diapers a day).

Treatment of Breastfeeding failure jaundice

The best treatment for breastfeeding failure jaundice in otherwise healthy full-term newborns is to increase the frequency and duration of feeds to stimulate milk production, maintain adequate hydration, and promote bilirubin excretion.

Neonates should breastfeed 8-12 times a day (every 2-3 hours) for ~10-20 minutes per breast during the first month of life.

When bilirubin is eliminated as fecal urobilinogen, less bilirubin is reabsorbed and recycled in the enterohepatic circulation, thereby decreasing serum bilirubin levels.

If the bilirubin continues to rise despite efforts to optimize lactation, formula supplementation may be necessary.

Rectal bleeding should stop within 2 weeks of eliminating maternal dairy and soy products or switching to a hydrolyzed formula.

• Spontaneous resolution by age 1 year

Necrotizing enterocolitis (NEC)

It is the most common gastrointestinal emergency in the neonatal intensive care unit.

Clinical findings depend on the location and extent of intestinal damage.

Initial signs may be nonspecific, such as the hypothermia and lethargy but patient can also have characteristic gastrointestinal symptoms (eg, vomiting, residual milk in the stomach, abdominal distension).

Pathogenesis: involves a combination of gut immaturity and exposure to bacteria from enteral feeds, leading to a cascade of inflammation and damage to the bowel wall.

The premature intestinal mucosa is thought to have increased permeability and bacterial penetration.

In addition, immature local host defenses and decreased motllity allow for bacterial overgrowth.

If possible, premature infants should receive breast milk instead of formula,as breast milk may counteract some of the problems associated with gut immaturity.

However, the optimal timing of enteral feeding initiation and rate of advancement remains unclear, and premature infants, especially <32 weeks gestation, remain vulnerable to NEC and its complications

X-ray Findings in NEC

In NEC, the air is visible in the bowel wall ("double line" or "train-track" appearance), leading to the hallmark finding of pneumatosis intestinalis on x-ray.

Linear, branching areas of lucency over the liver are also abnormal and represent portal venous air.

This results from gas produced by bacteria in the portal veins or by the transmigration of gas from the bowel wall to mesenteric veins and into the portal vein.

causes irritability, depression, dermatitis, and stomatitis. It can also cause an elevated serum homocysteine concentration, which is a known risk factor for venous thromboembolic disease and atherosclerosis.

Deficiency of riboflavin (vitamin B2 ):

Can lead to cheilosis, glossitis, seborrheic dermatitis (often affecting the genital areas), pharyngitis, and edema and/or erythema of the mouth.

Deficiency of thiamine (vitamin B1):

Causes beriberi or Wernicke-Korsakoff syndrome. These conditions are characterized by neurologic and psychiatric symptoms, and are often seen in alcoholics or patients who have had weight loss surgery.

Reye syndrome

Pathophysiology:

Microvesicular fatty infiltration & hepatic mitochondrial dysfunction

Etiology:

Pediatric(less than 15 yrs ) aspirin use in the setting of influenza or varicella infection

Aspirin is a mitochondrial toxin that can cause acute hepatic dysfunction in young individuals.

Pathogenesis: It present 3-7 days after surgery. The underlying mechanism is likely related to interruption of the autonomic nervous system, possibly due to anesthesia, analgesia, or surgical trauma. As a result. colonic dilation occurs, usually involving the cecum and ascending colon, although the entire colon may be involved. Increasing colonic dilation increases the risk of colonic ischemia and perforation.